MKVToolNix is an open source application for working with Matroska media files. Matroska itself is a container format based on an open source standard by the non-profit Matroska organization.

Matroska is a very flexible format that can contain any number of video, audio and subtitle tracks. It supports advanced features such: the latest video and audio codecs; complex chapter structures; attachments; an extensive tagging system; and comprehensive track header fields.

MKVToolNix consists of multiple tools in one program: the multiplexer used to create Matroska files; the info tool for inspecting existing Matroska files on an element-by-element level; a powerful editor for chapter structures; a header editor for changing file & track headers as well as modifying attachments; and a job queue for processing long-running processes in the background.

Also included are command-line programs corresponding to the tools mentioned above. These can be used as a basis for arbitrarily complex automation tasks such as batch multiplexing whole movie libraries.

Features:

• Create Matroska media files from wide range of video, audio and subtitle files
• Create complex chapter structures with a powerful chapter editor
• Edit the headers & attachments of existing Matroska files
• Supported video codecs: AV1, AVC/H.264, HEVC/H.265, MPEG-1/2/4, Theora, VC1, VP8, VP9 and many more
• Supported audio codecs: AAC, AC-3, ALAC, DTS, FLAC, MP3, Opus, PCM, ProRes, TrueAudio, TrueHD, Vorbis and many more
• Supported subtitle formats: ASS/SSA, PGS, SRT, VobSub and many more
• Supported container formats: AVI, Matroska, MP4, MPEG transport streams, MPEG program streams, various elementary streams and many more.